On Reducing the Somatogravic Illusion with Hmd Conveyed Visual Flow

Abstract

The acceleration-induced somatogravic illusion (SGI) is part of the pilot spatial disorientation (SD) problem. The effect of visual flow on the SGI was investigated in 13 non-pilots equipped with a head-tracked head-mounted display (HMD) in a human-use centrifuge. The participant was seated in a fixed gondola facing the rotation center of rotation of the centrifuge, and by increasing the angular speed of the centrifuge the centripetal acceleration was increased from near-zero to 0.57Gx. The final gravitoinertial force vector was 1.15G corresponding to a 30° pitch-up. During acceleration of the centrifuge, the participant viewed either a HMD presentation of moving texture elements beneath a stationary horizon, representing a forward linear acceleration, or a darkened HMD without any orientation cues. By means of an adjustable plate the participant continually indicated the perceived horizontal plane. Although there was a great inter-individual variability in the magnitude of the SGI, the overall results suggest that HMD conveyed visual flow might reduce SGI in non-pilots.